It's-a-me again, with one more suggestion!
(don't get me wrong, I'm enjoying Coppermine A LOT! And that's exactly why I'm suggesting this many improvements... XD)
I did some batch uploading of flash files today, and had some problems on the image display (more details here: http://forum.coppermine-gallery.net/index.php?topic=29289.0)
After batch uploading, I had to edit the descriptions, so I entered that batch edit images per-album (very practical).
There, to each file, the first atribute you can change is width and heigh.
My suggestion is to make this exactly like config panel does to reduced pictures: You give only one number or dimension, and that will be the size of the greatest (max) dimension.
This avoids blank unused spaces on the image display, as the frame will fit to the picture, using the number you gave to the max dimension, and fitting whatever the minimum dimension is.
That's it!
Anyways, you know, those are just suggestions for a future version, when you have the time to do those changes. Coppermine is already great the way it is! :D